CN110062999B - Active filter device built-in equipment - Google Patents

Active filter device built-in equipment Download PDF

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Publication number
CN110062999B
CN110062999B CN201780069144.4A CN201780069144A CN110062999B CN 110062999 B CN110062999 B CN 110062999B CN 201780069144 A CN201780069144 A CN 201780069144A CN 110062999 B CN110062999 B CN 110062999B
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Prior art keywords
current
active filter
filter device
power supply
power
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CN201780069144.4A
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CN110062999A (en
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河野雅树
川嶋玲二
藤田崇之
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Daikin Industries Ltd
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Daikin Industries Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/01—Arrangements for reducing harmonics or ripples
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00—Control or safety arrangements
    • F24F11/88—Electrical aspects, e.g. circuits
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/12—Arrangements for reducing harmonics from ac input or output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/20—Active power filtering [APF]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/40—Arrangements for reducing harmonics
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P80/00—Climate change mitigation technologies for sector-wide applications
    • Y02P80/10—Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Inverter Devices (AREA)
  • Supply And Distribution Of Alternating Current (AREA)
  • Power Conversion In General (AREA)
  • Rectifiers (AREA)

Abstract

The invention discloses an active filter device built-in device, which is internally provided with an active filter device (4) and is connected to an alternating current power supply (3). The active filter device (4) is configured to: the load information detection unit (5) operates on the basis of the detection value of the load information detection unit (5), and the load information detection unit (5) detects load information of the AC power supply (3) outside the active filter device-equipped apparatus.

Description

Active filter device built-in equipment
Technical Field
The invention relates to active filter device built-in equipment.
Background
In order to prevent harmonic current from flowing out to an electric power system (for example, an electric power system including a commercial power supply), an active filter device may be provided in an air conditioner or the like (for example, see patent document 1).
Patent document 1: japanese laid-open patent publication No. 2016-116330
Disclosure of Invention
Technical problems to be solved by the invention
However, in some cases, a load other than the air conditioner (for example, an apparatus having an inverter circuit or the like, such as an elevator or the like) is connected to the power system to which the air conditioner is connected, and the load other than the air conditioner may be a source of generation of harmonic current. In this case, it is not sufficient to take measures only for the harmonic current of the air conditioner, and it is necessary to take measures for the harmonic current of other equipment. Further, from the viewpoint of reducing the capacity of the equipment and saving energy, improvement of the fundamental power factor is required.
The invention aims to: in an active filter device built-in apparatus having an active filter device built therein, the active filter device can be made to function with respect to other loads including those different from the active filter device built-in apparatus.
Technical solution for solving technical problem
In order to solve the above problem, a first aspect relates to an active filter device-incorporating apparatus that incorporates an active filter device 4 and is connected to an ac power supply 3. The active filter device 4 is configured to: the load information detection unit 5 operates based on the detection value of the load information detection unit 5, and the load information detection unit 5 detects the load information of the ac power supply 3 outside the active filter device-equipped apparatus.
In this configuration, the active filter device 4 functions based on load information of the ac power supply 3 in the power system outside the device in which the active filter device is built.
On the basis of the first aspect, the second aspect is characterized in that: the active filter device 4 outputs a current for performing at least one of reduction of a harmonic current in the ac power supply 3 and improvement of a fundamental power factor in the ac power supply 3, based on the detection value.
In this configuration, the active filter device 4 reduces the harmonic current and improves the fundamental power factor.
On the basis of the first aspect, the third aspect is characterized in that: the operation of the active filter device 4 is controlled by a controller 43 installed in the active filter device built-in apparatus. The controller 43 determines the magnitude of the current Ic output from the active filter device 4 using the current value iq2 corresponding to the reactive current of the other load device 20 connected to the ac power supply 3 and the current values ir1 and it1 of the current flowing from the ac power supply 3 to the active filter device-equipped equipment.
In this configuration, the power factor is improved according to the reactive current of the other load device 20. Therefore, in the case where another load device is connected to the power system together with the air conditioner, improvement of the power factor can be achieved without increasing the capacity of the active filter device.
On the basis of the third aspect, the fourth aspect is characterized in that: the active filter device 4 uses only the fundamental component of the reactive current as the current value iq2 corresponding to the reactive current.
This configuration is suitable for improving the power factor in a configuration in which the harmonic current output from the other load device 20 is small or no harmonic current is output.
On the basis of the first aspect, the fifth aspect is characterized in that: the phase modulation equipment 200 is connected to the ac power supply 3, and the phase modulation equipment 200 is connected in parallel to the active filter device built-in equipment and is used to control the reactive power of the ac power supply 3. The active filtering means 4 operates according to at least one of the reactive power and the power factor of the alternating current power source 3 in order to improve the leading power factor due to the control of the reactive power by the phase modulation device 200.
In this configuration, in contrast to phase modulation apparatus 200, when active filter device 4 operates, the actual power supply power factor becomes a lagging power factor that lags behind the target power factor. Therefore, the situation that the actual power factor of the power source becomes a leading power factor leading the target power factor due to the control of the reactive power by the phase modulation device 200 is improved by controlling the operation of the active filter device 4. Thus, the phenomenon that the actual power factor becomes a leading power factor due to the phase modulation apparatus 200 is simply improved, so that appropriate compensation of the actual power factor and improvement of the fundamental power factor can be achieved. As a result, it is possible to suppress an increase in power consumption of the power system of the ac power supply 3 and reduce the possibility of occurrence of a problem such as an unnecessary increase in the system voltage.
On the basis of the first aspect, the sixth aspect is characterized in that: the magnitude of the current Ic output from the active filter device 4 is determined by using a current value iq corresponding to a reactive current of a load 10 and a phase modulation device 200 connected to the ac power supply 3, the load being other than the active filter device, and current values ir1 and it1 of a current flowing from the ac power supply 3 to the load 10.
In this configuration, the reactive current of the load and the phase modulation device other than the active filter device built-in device is grasped and the current Ic is made to flow, so that the reactive current is compensated.
On the basis of any one of the first to sixth aspects, the seventh aspect is characterized in that: the load information detection unit 5 is configured to detect the current values Irs and Its, and the transmission method of the detected current values Irs and Its is a wireless method.
In this configuration, the wiring can be omitted by using the wireless system.
On the basis of any one of the first to seventh aspects, the eighth aspect is characterized in that: the load information detection unit 5 operates without a power supply.
In this configuration, the wiring can be omitted by adopting the passive system.
A ninth aspect is, on the basis of any one of the first to eighth aspects, characterized in that: current detectors 4a, 4b, and 4c for detecting current values Irs, Iss, and Its are provided in the load information detection unit 5 corresponding to the phases R, S, T of the ac power supply 3.
In this configuration, even if the loads 1 and 2 are operated by single-phase ac, the current value can be reliably detected.
Effects of the invention
According to the first aspect, in the active filter device built-in apparatus having the active filter device built-in therein, the active filter device can also function on another load connected to the ac power supply, which is different from the active filter device built-in apparatus.
According to the second aspect, in the power system to which the plurality of loads are connected, at least one of reduction of the harmonic current and improvement of the fundamental wave power factor can be achieved.
According to the third aspect, the power factor can be improved while suppressing an increase in size of the active filter device.
According to the fourth aspect, in the load connected to the power system together with the active filter device built-in equipment, it is possible to generate the compensation current suitable for the case where no measure is required for the higher harmonic current.
According to the fifth aspect, the phenomenon that the actual power factor becomes a leading power factor due to the phase modulation apparatus is simply improved, so that appropriate compensation of the actual power factor and improvement of the fundamental power factor can be achieved. As a result, an increase in power consumption of the power system including the ac power supply can be suppressed, and the possibility of occurrence of a problem such as an unnecessary increase in the system voltage can be reduced.
According to the sixth aspect, the power factor in a building or the like having a phase modulation apparatus can be improved.
According to the seventh and eighth aspects, the apparatus can be easily set.
According to the ninth aspect, the above-described effects can be reliably obtained even if the load device is a device that operates on single-phase alternating current.
Drawings
Fig. 1 is a block diagram showing an air conditioning system according to a first embodiment.
Fig. 2 is a block diagram showing an example of the controller according to the first embodiment.
Fig. 3 is a block diagram showing an air conditioning system according to a second embodiment.
Fig. 4 is a block diagram showing an air conditioning system according to a third embodiment.
Fig. 5 is a block diagram showing an air conditioning system according to a fourth embodiment.
Fig. 6 is a block diagram showing a controller according to the fourth embodiment.
Fig. 7 is a block diagram showing an air conditioning system according to a fifth embodiment.
Fig. 8 is a block diagram showing an air conditioning system according to a modification of the fifth embodiment.
Fig. 9 is a block diagram showing an air conditioning system according to a sixth embodiment.
Fig. 10 schematically shows the structure of a phase modulation apparatus.
Fig. 11 is a block diagram showing a configuration of a power factor control system according to the seventh embodiment.
Fig. 12 is a block diagram showing the configuration of a controller of a phase modulation apparatus according to the seventh embodiment.
Fig. 13 is a conceptual diagram of a switching combination table of a phase modulator.
Fig. 14 is a diagram showing a state in which the active filter device is not compensated and a state in which the active filter device is compensated in the seventh embodiment.
Fig. 15 is a block diagram showing a configuration of an active filter controller according to the seventh embodiment.
Detailed Description
Embodiments of the present invention will be described below with reference to the drawings. The following embodiments are merely preferred examples in nature, and are not intended to limit the scope of the present invention, its application, or its uses.
(first embodiment of the invention)
Fig. 1 is a block diagram showing an air conditioning system 100 according to a first embodiment of the present invention. In this example, the air conditioning system 100 includes an air conditioning device 11 and an active filter device 4. The air conditioning system 100 is installed in an apartment, a factory, a building, a single-family house, or the like (hereinafter referred to as a building or the like), and conditions (cools or heats) indoor air using the air conditioner 11.
Power is supplied from a power system including the ac power supply 3 to a building or the like in which the air conditioner 11 is installed. In this example, the ac power supply 3 is a three-phase ac power supply (e.g., a three-phase commercial power supply), and supplies power to a plurality of loads (described later) in a divided manner. A distribution board 60 is provided in the building or the like, and the distribution board 60 is connected to the ac power supply 3 and receives ac power from the ac power supply 3. The distribution board 60 includes a plurality of circuit breakers, and supplies ac power from the ac power supply 3 to a plurality of devices through the respective circuit breakers. In this example, the air conditioner 11 is connected to one of the plurality of circuit breakers. The air conditioner 11 is operated by ac power supplied through the distribution board 60. That is, the air conditioning system 100 is an example of an active filter device-equipped device that incorporates the active filter device 4 and is connected to the ac power supply 3. The devices with built-in active filter devices include elevators, fans, pumps, escalators, and lighting driven by three-phase power supplies installed in buildings.
The distribution board 60 is connected to the load 2 in addition to the air conditioner 11. In this example, the load device 2 is a device having a circuit that becomes a harmonic current generation source such as an inverter circuit (this is called a harmonic generation load device). The load device 2 includes, for example, an elevator, a fan, a pump, an escalator, and lighting driven by a three-phase power supply installed in a building, and also includes, for example, other air conditioners different from the air conditioner 11, which do not take measures against harmonics by using an active filter device or the like.
< air conditioner 11 >
The air conditioner 11 includes a refrigerant circuit (not shown) having a compressor and the power conversion device 1, and the active filter device 4 is incorporated in the air conditioner 11. The power converter 1 is a load connected to an ac power supply 3, and the power converter 1 is an example of the harmonic generation load. The power conversion apparatus 1 is connected to an ac power supply 3 via a distribution board 60. The power conversion device 1 includes a converter circuit and an inverter circuit (both not shown). The ac power supplied to the power conversion device 1 is converted into ac power having a desired frequency and a desired voltage by the power conversion device 1, and then supplied to the compressor (more specifically, a motor included in the compressor). The compressor is thus operated, and the refrigerant circuit functions. As a result, the indoor air is conditioned.
When the power conversion device 1 and the motor of the compressor are operated, harmonic current may be generated in the air conditioner 11. The harmonic current may flow out to the ac power supply 3 through a current path for supplying power from the distribution board 60 to the air conditioner 11. In general, since the amount of harmonic current flowing out to the ac power supply 3 side is limited, the harmonic current flowing out to the ac power supply 3 side is reduced by the active filter device 4 in the air conditioning system 100. In addition, from the viewpoint of equipment capacity, energy saving, and the like, it is necessary to improve the fundamental wave power factor at the distribution side and the power reception side, and the active filter device 4 of the present embodiment also has a function of improving the fundamental wave power factor. The structure of the active filter device 4 will be explained below.
< active filter device 4 >
The active filter device 4 is incorporated in the air conditioner 11, and has a function of canceling out the harmonic current flowing from the harmonic-generating load. That is, the active filter device 4 allows a current (compensation current) to flow so that the current in a current path (hereinafter, also referred to as a power receiving path) connecting the ac power supply 3 and the distribution board 60 approaches a sine wave. More specifically, the harmonic current appearing in the power receiving path is detected, and a compensation current having a phase opposite to that of the detected harmonic current is generated and supplied to the power receiving path (power receiving path 12 in fig. 1) of the air conditioner 11.
It is generally believed that: when the load of the air conditioner 11 is maximum (for example, when the cooling output is maximum), the harmonic current generated in the air conditioner 11 is maximum. Therefore, the capacity (the amount of power that can be generated) of the active filter device 4 is set in accordance with the harmonic current when the load of the air conditioner 11 is at a maximum. In general, there are more cases where the air conditioner 11 is used in the maximum load state than when the air conditioner 11 is used in the medium load state, and therefore it is conceivable that: if the active filter device 4 with the utilization capability set in this way takes measures only for the harmonic current of the air conditioner 11, the period of time during which the capability of the active filter device 4 is excessive is large.
The active filter device 4 has a function of improving the fundamental power factor. In this example, the active filter device 4 is configured to improve the fundamental power factor by flowing a compensation current for compensating also the reactive component of the fundamental wave. In order to realize the above-described functions of the active filter device 4, as shown in fig. 1, the active filter device 4 of the present embodiment includes a current source 30, a controller 43, a voltage detector 46, a first current detection unit 5, and a second current detection unit 47.
Voltage detector, current detection section
The voltage detector 46 is a sensor that detects the voltage Vrs of the ac power supply 3.
The second current detection unit 47 is used to detect the current value (hereinafter referred to as current values Ir2a, It2 a) input to the active filter device 4. In this example, the second current detection portion 47 includes a current detector 45a and a current detector 45 b. The current detector 45a detects a current value Ir2a of the R-phase input from the ac power supply 3 to the active filter device 4, and the current detector 45b detects a current value It2a of the T-phase input from the ac power supply 3 to the active filter device 4. The detection values of the current detectors 45a and 45b are sent to the controller 43 (more specifically, a second current calculation unit 434 described later).
The structure of each of the current detectors 45a and 45b is not particularly limited, and it is conceivable to use a current transformer or the like, for example. The current detectors 45a and 45b may be configured to transmit the detected values to the controller 43 in a wired manner, or may be configured to transmit the detected values to the controller 43 in a wireless manner. Although the current detectors 45a and 45b constituting the second current detection unit 47 shown in fig. 1 are for detecting two-phase currents, there is no problem in the configuration in which three current detectors are provided in the second current detection unit 47 to detect three-phase currents.
On the other hand, the first current detection unit 5 is an example of a load information detection unit, and detects a current value in the power reception path 12 of the air conditioner 11. Specifically, the first current detection unit 5 detects the current value of the ac power supply 3 before the current from the ac power supply 3 is shunted to each load (harmonic generation load). In this example, the first current detection unit 5 includes a current detector 4a and a current detector 4 b. The current detectors 4a and 4b detect the current of the ac power supply 3 before the input to the distribution board 60. More specifically, the current detector 4a detects a current value Irs of the R-phase of the ac power supply 3, and the current detector 4b detects a current value Its of the T-phase of the ac power supply 3. The detection values of the current detectors 4a and 4b are sent to the controller 43 (more specifically, a first current calculation unit 435 described later).
The structure of each of the current detectors 4a and 4b is not particularly limited, and it is conceivable to use a current transformer or the like, for example. The current detectors 4a and 4b may be configured to transmit the detection values to the controller 43 in a wired manner, or may be configured to transmit the detection values to the controller 43 in a wireless manner.
The first current detection unit 5 may be provided inside the distribution board 60 or may be provided outside the distribution board 60. In the present embodiment, the current detectors 4a and 4b are provided in the distribution board 60. By providing the current detectors 4a and 4b in the distribution board 60, the current detectors 4a and 4b are not exposed to the weather, and therefore, the reliability of the current detectors 4a and 4b is improved, and the service life of the current detectors 4a and 4b is prolonged. The detection values of the current detectors 4a and 4b are wirelessly transmitted to the controller 43. The distance between the distribution board 60 and the air conditioner 11 may be 20 to 30 meters. Therefore, it takes considerable time and effort to connect the current detectors 4a, 4b and the air conditioner 11 in the distribution board 60 in a wired manner. In contrast, in the present embodiment, since the detection values of the current detectors 4a and 4b are wirelessly transmitted to the controller 43, the number of processes for wired connection can be reduced.
The magnetic flux passing through the current detectors 4a and 4b changes with time due to the current flowing through the current detectors 4a and 4b, and this phenomenon is referred to as electromagnetic induction. The induced electromotive force, which is the electromotive force generated by the electromagnetic induction, may be used as a power source (for example, a power source for communication) for operating the first current detection unit 5. Thus, the first current detection unit 5 can be operated without a power supply (i.e., the first current detection unit 5 does not require an external power supply). The first current detection unit 5 can be operated without a power supply, and thus, time and effort required for the operation can be reduced.
-current source 30-
The current source 30 generates a current (i.e., a compensation current) for reducing the higher harmonic current and improving the fundamental power factor. The output terminal of the current source 30 is connected to the power reception path 12 of the power conversion device 1, and the generated compensation current is output to the power reception path 12. The current source 30 of the present embodiment is constituted by a so-called inverter circuit. A switching command value G described later is input from the controller 43 to the current source 30. The current source 30 is turned on and off according to the switching command value G to generate a compensation current.
Controller 43
Fig. 2 is a block diagram showing an example of the controller 43 according to the first embodiment. The controller 43 controls the output current of the current source 30. In this example, the controller 43 includes: a gate pulse generator 431, a current command calculation unit 432, a load current calculation unit 433, a second current calculation unit 434, a first current calculation unit 435, and a phase detection unit 436. The controller 43 can be constituted by, for example, a microcomputer and a memory storing a program for operating the microcomputer.
The voltage Vrs detected by the voltage detector 46 is input to the phase detection unit 436, and the phase detection unit 436 detects the phase of the power supply voltage in the power reception path 12 and transmits the detected phase to the first current calculation unit 435 and the second current calculation unit 434.
The first current calculation unit 435 obtains a current (referred to as a first current value i 1) necessary when both compensation of the harmonic current (reduction of the harmonic current) and compensation of the reactive component of the fundamental wave (improvement of the fundamental wave power factor) are performed, based on the phase detected by the phase detection unit 436 and the current values Irs, Its detected by the current detectors 4a, 4b, and outputs the first current value i1 to the load current calculation unit 433. More specifically, the harmonic current component and the reactive component of the fundamental wave are extracted from the detection values (current values Irs, Its) of the current detectors 4a and 4b, and then output as the first current value i 1.
The second current calculation unit 434 obtains a current (referred to as a second current value i 2) flowing into the active filter device 4 from the phase detected by the phase detection unit 436 and the current values Ir2a and It2a detected by the current detectors 45a and 45b, and outputs the second current value i2 to the load current calculation unit 433. The active filter device 4 compensates for the harmonic current at that time (reduction in harmonic current) and also compensates for the reactive component of the fundamental wave (improvement in fundamental power factor). More specifically, the harmonic current component and the reactive component of the fundamental wave are extracted from the detection values (current values Ir2a, It2 a) of the current detectors 45a and 45b, and then output as the second current value i 2.
The load current calculation unit 433 calculates currents flowing through the load device 2 (three-phase harmonic generation load device) and the power conversion apparatus 1 (harmonic generation load device). Here, the following relational expressions hold true for the R-phase, the S-phase, and the T-phase among the current values Ir1L, Is1L, and It1L of the respective phases input to the load 2, which Is an example of one of the three-phase harmonic wave generation loads, the current values Ir2, Is2, and It2 of the respective phases input to the air conditioning apparatus 11, the current values Ir2L, Is2L, and It2L of the respective phases input to the power conversion apparatus 1 (i.e., the harmonic wave generation load), and the current values Ir2a, Is2a, and It2a of the respective phases input to the active filter apparatus 4.
And (3) phase R: irs = Ir1L + Ir2= Ir1L + Ir2L + Ir2a
And (3) S phase: iss = Is1L + Is2= Is1L + Is2L + Is2a
Phase T: its = It1L + It2= It1L + It2L + It2a
As Is apparent from the above relational expression, the following expression holds when the current values Ir2a, Is2a, and It2a of the respective phases input to the active filter device 4 are subtracted from the current values Irs, Iss, and It of the respective phases flowing through the ac power supply 3.
And (3) phase R: Irs-Ir2a = Ir1L + Ir2-Ir2a = Ir1L + Ir2L + Ir2a-Ir2a
And (3) S phase: Iss-Is2a = Is1L + Is2-Is2a = Is1L + Is2L + Is2a-Is2a
Phase T: Its-It2a = It1L + It2-It2a = It1L + It2L + It2a-It2a
After the above equation (2) is arranged, the following relational expression is obtained.
Irs-Ir2a=Ir1L+Ir2L
Iss-Is2a=Is1L+Is2L......（3）
Its-It2a=It1L+It2L
As Is clear from the above equation (3), the currents flowing through the load device 2 (three-phase harmonic generation load device) and the power conversion device 1 (harmonic generation load device) can be obtained by subtracting the current values Ir2a, Is2a, It2a of the respective phases input to the active filter device 4 from the current values Irs, Iss, It of the respective phases flowing through the ac power supply 3. In the present embodiment, the fundamental wave power factors of the load device 2 and the power conversion device 1 and the harmonics generated in the load device 2 and the power conversion device 1 are suppressed by this point, and the fundamental wave power factors of the power distribution side and the power reception side near the ac power supply 3 are improved and the harmonic currents are reduced. Specifically, in the present embodiment, the load current calculation unit 433 calculates the current flowing through the load device 2 and the power conversion device 1, and outputs the current to the current command calculation unit 432. Specifically, load current calculating unit 433 calculates first current value i1 to second current value i2, and outputs the calculated values to current command calculating unit 432.
The current command calculation unit 432 calculates a current value in reverse phase to the current calculated by the load current calculation unit 433, and outputs the current value to the gate pulse generator 431 as a current command value Iref. The gate pulse generator 431 generates a switching command value G that instructs the inverter circuit constituting the current source 30 to be turned on and off. Specifically, the gate pulse generator 431 performs feedback control, and under this feedback control, the operation of generating the switching command value G in accordance with the deviation between the output current value of the current source 30 and the current command value Iref is repeated. Thereby, a current (compensation current) corresponding to the current command value Iref is supplied from the current source 30 to the power receiving path 12. More specifically, the gate pulse generator 431 outputs the switching command value G to the current source 30 so that the second current value i2 obtained by the second current calculation unit 434 matches the current command value Iref. As a result, harmonic components contained in the current flowing through the load device 2 and the power conversion device 1 cancel the current output from the active filter device 4, and the current flowing from the ac power supply 3 becomes a sine wave from which the harmonic current is removed, thereby improving the power factor.
< working situation of the active filter means 4 >
Since the active filter device 4 is incorporated in the air conditioning system 100, the active filter device 4 enters an operating state upon energization of the air conditioning system 100.
Upon generation of the current command value Iref, the current command calculation unit 432 generates a switching command value G, and the gate pulse generator 431 outputs a compensation current corresponding to the current command value Iref from the current source 30 to the power reception path 12. In the present embodiment, not only the harmonic current caused by the air conditioner 11 can be reduced to improve the fundamental power factor caused by the air conditioner 11, but also the harmonic current caused by the other load devices 2 can be reduced to improve the fundamental power factor caused by the other load devices 2.
< Effect of the present embodiment >
As described above, according to the present embodiment, in the power system in which a plurality of loads (here, the power conversion device 1 and the load 2) are connected, the harmonic current can be reduced. In the present embodiment, the fundamental power factor can be improved.
(second embodiment of the invention)
Fig. 3 is a block diagram showing an air conditioning system 100 according to a second embodiment of the present invention. The difference from the first embodiment is that the other load device 21, which is a harmonic generation load device, is a device driven by a single-phase voltage, and the other load device 21 is assumed to be a lighting device such as an LED, a single-phase fan pump, or the like. In the present embodiment, assuming that the phase to which the other load 21, that is, the device driven by a single-phase voltage is connected is unknown, the first current detection unit 5 is provided with three current detectors 4a, 4b, and 4c to detect the current value of each phase R, S, T of the ac power supply 3 (that is, the current value of all three phases). That is, in this configuration, even if the load 21 is operated by a single-phase ac, the current value can be reliably detected.
With the above configuration, according to the present embodiment, when another load 21 of a single phase is connected to the air conditioning system 100 together with the air conditioning apparatus 11, it is possible to reduce the harmonic current. In the present embodiment, the fundamental power factor can be improved.
When the phase of the ac power supply 3 to which the single-phase load 21 is connected is known in advance, the first current detector 5 may be configured to: the current detectors 4a, 4b are provided for only two phases connected to the load 21, respectively.
(third embodiment of the invention)
Fig. 4 is a block diagram showing an air conditioning system 100 according to a third embodiment of the present invention. The difference from the first embodiment is that a plurality of loads are connected to the power system as shown in fig. 4. Specifically, the power system is connected with a three-phase harmonic generation load device, i.e., a load device 22, and a three-phase harmonic generation load device, i.e., a load device 21. That is, in the present embodiment, two harmonic generation loads (three phases) are provided in addition to the power conversion device 1. As described above, even if there are a plurality of harmonic-generating loads (three phases), the same effects can be obtained by performing the same control as in the first embodiment. That is, according to the present embodiment, when the air conditioning system 100 is connected to the air conditioning apparatus 11 together with the plurality of other loads 21 and 22, the harmonic current can be reduced. In the present embodiment, the fundamental power factor can be improved.
(fourth embodiment of the invention)
Fig. 5 is a block diagram showing an air conditioning system 100 according to a fourth embodiment of the present invention. The difference from the first embodiment is that, as shown in fig. 5, a plurality of (two in this example) air conditioners 11, 11 are provided in the power system. In this example, the air conditioners 11, 11 each include a source filter device 4. Since a plurality of air conditioners 11 are provided, the current sharing capacity of the active filter device 4 can be reduced. As a result, the present embodiment has the following effects: the current capacity of the active filter device 4 can be reduced to reduce the cost, and the size can be reduced.
Fig. 6 is an example of a block diagram showing the controller 43 according to the present embodiment. The difference from the first embodiment is that the current values Irs, Its of the respective phases flowing through the ac power supply 3 detected by the current detectors 4a, 4b are input to the number-of-units calculating unit 437 of the controller 43. In order to reduce the harmonic current of the load 21, which is a harmonic generation load, and improve the power factor, the number-of-devices calculation unit 437 considers the number of active filter devices 4 that are responsible for reducing the harmonic current and improving the power factor. In the present embodiment, one load device 21 (i.e., a harmonic-generating load device) includes two active filter devices 4, and the number-of-devices calculation unit 437 outputs, to the first current calculation unit 435, values obtained by dividing the current value Irs and the current value Its detected by the current detectors 4a and 4b by 2, respectively, on the assumption that the current capacities of the active filter devices 4 are equal to each other. This makes it possible to obtain the compensation current for each phase shared by one active filter device 4. In this example, the output power of each active filter device 4 is half of that when one active filter device 4 outputs the compensation current.
When the current capacities of the active filter devices 4 are not equal to each other, the current to be shared is obtained from the current capacities. For example, assuming that the current capacity of one active filter device 4 is 10kW and the current capacity of the other active filter device 4 is 50kW, the number-of-active-filter-device-4 calculation unit 437 having a current capacity of 10kW outputs values obtained by dividing the current value Irs and the current value Its detected by the current detectors 4a and 4b by 6 to the first current calculation unit 435. The first current calculation unit 435 outputs a first current value i1 based on the value sent from the number calculation unit 437. The number-of-active-filter-devices-4 calculation unit 437 of 50kW outputs to the first current calculation unit 435 a value obtained by multiplying 5/6 by the current values Irs, Its detected by the current detectors 4a and 4 b. The first current calculation unit 435 outputs a first current value i1 based on the value sent from the number calculation unit 437. The output power of each active filter device 4 is lower than when one active filter device 4 is used to output the compensation current.
As described above, according to the present embodiment, when the plurality of air conditioners 11 and 11 are connected to the power system together with the other loads 21, the harmonic current can be reduced. In the present embodiment, the fundamental power factor can be improved.
(fifth embodiment of the invention)
Fig. 7 is a block diagram showing an air conditioning system 100 according to a fifth embodiment of the present invention. The air conditioning system 100 is an example of an active filter device-equipped device, and incorporates an air conditioning device 11 and an active filter device 4. The air conditioning system 100 is installed in a building, a factory, an apartment, a single-family house, or the like (hereinafter referred to as a building or the like). Power is supplied to a building or the like from a power system including an ac power supply 3. In this example, the ac power supply 3 is a three-phase ac power supply (commercial power supply).
A distribution board 60 is provided in the building or the like, and the distribution board 60 is connected to the ac power supply 3 and receives ac power from the ac power supply 3. The distribution board 60 includes a plurality of circuit breakers, and distributes the ac power from the ac power supply 3 to a plurality of devices via the respective circuit breakers. In this example, the air conditioning system 100 is connected to one of the plurality of circuit breakers. The air conditioning system 100 is operated by ac power supplied through the distribution board 60.
Specifically, the air conditioner 11 includes a refrigerant circuit (not shown) and cools or heats each room in a building or the like. In this refrigerant circuit, a refrigerant circulates to perform a refrigeration cycle operation. The refrigerant circuit of the air conditioner 11 includes a compressor for compressing a refrigerant. As shown in fig. 7, the air conditioner 11 includes a converter circuit 511, a reactor 512, a capacitor 513, an inverter circuit 514, and a motor 515.
The converter circuit 511 is a circuit for converting ac to dc. For example, the converter circuit 511 is constituted by a diode bridge circuit. The capacitor 513 is used to smooth the output of the converter circuit 511. The inverter circuit 514 converts the dc smoothed by the capacitor 513 into an ac having a predetermined frequency and a predetermined voltage. Specifically, the inverter circuit 514 includes a plurality of (six in this case) switching elements connected in a bridge manner, and converts a direct current into an alternating current by controlling on/off of an input direct current.
The Motor 515 of the air conditioner 11 is a so-called Interior Permanent Magnet Motor (IPM Motor). The motor 515 drives the compressor. Here, if the motor 515 Is operated without any processing, the harmonic current Is added to the current of the power system (hereinafter referred to as a system current Is).
Another load device 20 different from the air conditioner 11 is also connected to one of the circuit breakers. Here, an example of the load device 20 is an elevator. As shown in fig. 7, the elevator includes a converter circuit 521, a reactor 522, a capacitor 523, an inverter circuit 524, and a motor 525. The inverter circuit 521 converts ac to dc, and has the same configuration as the inverter circuit 511 of the air conditioner 11. The capacitor 523 smoothes the output of the inverter circuit 521. The inverter circuit 524 converts the dc smoothed by the capacitor 523 into an ac having a predetermined frequency and a predetermined voltage. The inverter circuit 524 has the same configuration as the converter circuit 511. The motor 525 is also a so-called IPM motor, driving the elevator. Here, if the motor 525 operates without any processing, a higher harmonic current Is added to the system current Is.
< Structure of active Filter device >
As shown in fig. 7, the active filter device 4 includes a current source 5110, a power factor controller 5120, and a Pulse Width Modulation (PWM) controller 5140. In this example, the active filter device 4 is incorporated in the air conditioning system 100 together with the air conditioning device 11. The active filter device 4 allows a compensation current Ic, which will be described later, to flow through the power supply system, thereby improving the power factor and suppressing harmonics of the air conditioner 11. Here, as an example of the compensation current Ic, a direction from the active filter device 4 to the ac power supply 3 is set to be positive. Further, the sum of the system current Is and the compensation current Ic Is equal to the sum of the current (load current I1) flowing from the power supply system (ac power supply 3) to the air conditioner 11 and the current (load current I2) flowing from the power supply system (ac power supply 3) to the load 20.
-current source 5110-
The current source 5110 includes an inverter circuit 5111 and a capacitor 5113. The capacitor 5113 is formed of, for example, an electrolytic capacitor. The inverter circuit 5111 charges and discharges the capacitor 5113 by inputting and outputting the compensation current Ic. In this example, the inverter circuit 5111 is connected to the ac power supply 3 via a three-phase reactor 5160.
In the inverter circuit 5111 of the present embodiment, six switching elements 5112 are connected in a bridge manner, and illustration thereof is omitted. The inverter circuit 5111 changes the on/off states (on/off states) of the plurality of switching elements 5112 in synchronization with a carrier signal having a predetermined frequency, and inputs and outputs the compensation current Ic. On-off control of the switching element 5112 is performed by the PWM controller 5140. In this example, a low-pass filter 5150 is provided between the reactor 5160 and the connection point between the circuit breaker and the air conditioner 11 for the purpose of removing the ripple of the compensation current Ic. The low-pass filter 5150 is a so-called LC filter.
Power factor controller 5120
The power factor controller 5120 includes a power source phase detector 5121, a phase calculation unit 5122, three current sensors 5123, 5124, 5125, three dq converters 5126, 5127, 5128, a high-pass filter 5129, two adders 5130, 5132, three subtractors 5131, 5133, 5135, a voltage controller 5134, and two current controllers 5136, 5137. Specifically, the main portion of the power factor controller 5120 may be configured by a microcomputer, a memory in which software for operating the microcomputer is stored, and the like.
The power supply phase detector 5121 is connected to predetermined lines (any two of r-phase, s-phase, and t-phase) of the ac power supply 3, detects the phase of the line voltage, and outputs the detected phase to the phase calculation unit 5122. The phase calculation unit 5122 obtains the phase ω t between the lines connected to the power phase detector 5121 by using a signal (referred to as zero-cross signal S1) output from the power phase detector 5121. The phase calculation unit 5122 outputs the obtained phase ω t to the dq converters 5126, 5127, and 5128.
The current sensor 5123 is provided outside the air conditioning system 100 and detects the load current I1. The load current I1 is a three-phase current, but the current sensor 5123 detects load currents ir1 and it1 of two phases of the three phases. The current sensor 5124 detects the compensation current Ic. The compensation current Ic is also a three-phase current, but the current sensor 5124 detects load currents of two phases of the three phases. Further, the current sensor 5125 is provided outside the air conditioning system 100, and detects the load current I2. The load current I2 is also a three-phase current, but the current sensor 5125 detects load currents ir2, it2 of two of the three phases. Note that, if the load currents I1, I2, and the compensation current Ic detect the current values of two phases of three phases, the current value of the remaining phase can be easily calculated, and therefore each of the current sensors 5123, 5124, and 5125 may have a structure capable of detecting the current of two phases. As the current sensors 5123, 5124, and 5125, current sensors having various configurations can be used. As examples of the current sensors 5123, 5124, and 5125, a current transformer can be given. Further, the detection value of the current sensor 5125 may be wirelessly transmitted to the dq converter 5128.
The dq converter 5126 performs three-phase/two-phase conversion (dq-axis conversion) on the load current I1 (three phase) obtained from the detection value of the current sensor 5123. Here, the d-axis and the q-axis are axes in a rotational coordinate system that rotates in synchronization with the phase ω t obtained by the phase calculation unit 5122. The q-axis component (hereinafter referred to as q-axis component iq 1) obtained as a result of the conversion by the dq converter 5126 is a reactive current in the air conditioner 11. On the other hand, the d-axis component obtained as a result of the conversion is an active current in the air conditioner 11. The dq converter 5126 outputs the q-axis component iq1 to the adder 5130 and the d-axis component to the high-pass filter 5129.
The dq converter 5127 performs three-phase/two-phase conversion on the compensation current Ic obtained from the detection value of the current sensor 5124 to obtain a d-axis component (hereinafter referred to as d-axis current id) which is an active current and a q-axis component (hereinafter referred to as q-axis current iq) which is a reactive current. The d-axis current id is output to the subtractor 5135, and the q-axis current iq is output to the subtractor 5131.
The dq converter 5128 performs three-phase/two-phase conversion on the load current I2 (three phases) obtained from the detection value of the current sensor 5125 to obtain a q-axis component iq2 ″. The q-axis component iq2 is the reactive current in the load 20. The q-axis component iq2 obtained by the dq converter 5128 is output to the adder 5130. Thus, the adder 5130 outputs the added value of the q-axis component iq1 and the q-axis component iq 2. It can be considered that: the sum is a total value of reactive currents in a building or the like in which the active filter device 4 is installed. That is, it can be considered that: the added value is a q-axis component of the current that should be allowed to flow as the compensation current Ic. Hereinafter, this added value is referred to as a q-axis current command value iq.
The high-pass filter 5129 removes a dc component from the d-axis component of the load current I1 output from the dq converter 5126, and outputs the dc component to the adder 5132. If there is no higher harmonic component in the load current I1, the output of the dq converter 5126 is dc. This is because the component of the load current I1 synchronized with the phase of the ac power supply 3 appears as a direct current. That is, the high-pass filter 5129 outputs only the harmonic component included in the d-axis component of the load current I1 to the adder 5132.
If the compensation current Ic is made to flow so that the d-axis component and the q-axis component in the compensation current Ic match the harmonic component of the load current I1, the harmonic component of the load current I1 can be cancelled (hereinafter, the case where a current is made to flow so as to ensure cancellation of a predetermined component is referred to as compensation). That is, the output of the high-pass filter 5129 can be used to generate a command value (d-axis current command value id ×) of the d-axis component (d-axis current id) of the compensation current Ic.
On the other hand, the q-axis component iq1 of the load current I1 output from the dq converter 5126 also includes a dc component. Therefore, by superimposing the current corresponding to the q-axis component iq1 on the compensation current Ic, the harmonic component included in the load current I1 can be reduced, and the fundamental power factor can be improved.
In this example, the output of the high-pass filter 5129 is corrected so that the output of the high-pass filter 5129 corresponds to a change in the voltage between the terminals of the capacitor 5113 (hereinafter, referred to as a dc voltage Vdc), instead of directly using the output of the high-pass filter 5129 as the d-axis current command value id. Specifically, in the power factor controller 5120, a subtractor 5133 first determines a deviation between the dc voltage Vdc of the capacitor 5113 and the command value Vdc thereof. The voltage controller 5134 performs proportional-integral control based on the deviation obtained by the subtractor 5133 to obtain a correction value. The correction value is added to the output of the high-pass filter 5129 in the adder 5132, and the addition result is output as a d-axis current command value id. The influence of the variation of the dc voltage Vdc is reduced.
A subtractor 5135 calculates a deviation Δ id obtained by subtracting the d-axis current id from the d-axis current command value id, and outputs the deviation Δ id to the current controller 5136; a subtractor 5131 calculates a deviation Δ iq obtained by subtracting the q-axis current iq from the q-axis component iq1, and outputs the deviation Δ iq to the current controller 5137.
The current controller 5136 outputs a d-axis voltage command value Vid, which is one of the voltage command values of the two phases, by an algorithm such as feedback control (for example, so-called PID control) based on the deviation Δ id. The current controller 5137 outputs a q-axis voltage command value Viq, which is one of the voltage command values of the two phases, by an algorithm such as feedback control (for example, so-called PID control) based on the deviation Δ iq.
PWM controller 5140-
The PWM controller 5140 generates a switching command value (drive signal G) for driving the current source 5110 based on the d-axis voltage command value Vid and the q-axis voltage command value Viq. Specifically, the PWM controller 5140 performs so-called Pulse Width Modulation (PWM) control, and causes the current source 5110 to input and output the compensation current Ic. The PWM controller 5140 can be configured by a microcomputer, a memory in which software for operating the microcomputer is stored, and the like.
< working conditions of active filtering device >
Since active filter device 4 is incorporated in air conditioning system 100, power is supplied to air conditioning system 100 to operate active filter device 4. Then, the power factor controller 5120 of the active filter device 4 obtains the q-axis component iq1 of the load current I1 from the detection value of the current sensor 5123 and the like. The q-axis component iq2 can also be obtained by the dq converter 5128 from the detection value of the current sensor 5125.
The adder 5130 adds the q-axis component iq1 of the load current I1 and the q-axis component iq2 of the load current I2, and outputs the resultant as a q-axis current command value iq. The subtractor 5131 subtracts the q-axis current iq obtained by the dq converter 5127 from the q-axis current command value iq, and outputs the result as a deviation Δ iq.
In the power factor controller 5120, the d-axis current command value id is generated by the operation of the dq converter 5126 or the like. The subtractor 5135 subtracts the d-axis current id obtained by the dq converter 5127 from the d-axis current command value id, and outputs the d-axis current id as the deviation Δ id.
Upon determination of the deviation Δ id, a d-axis voltage command value Vid is output from the current controller 5136; as soon as the deviation Δ iq is determined, the q-axis voltage command value Viq is output from the current controller 5137. As a result, the PWM controller 5140 outputs the drive signal G corresponding to the d-axis voltage command value Vid and the q-axis voltage command value Viq to the inverter circuit 5111. As a result, the compensation current Ic having components corresponding to the d-axis current command value id and the q-axis current command value iq flows from the current source 5110. Thus, the harmonic current generated by the air conditioner 11 and contained in the system current Is reduced, and the fundamental power factor Is improved.
< Effect of the present embodiment >
As described above, in the present embodiment, the harmonic component of the active current and the reactive current of the air conditioner 11 are compensated for, and the harmonic current and the power factor are reduced. On the other hand, the other loads 20 connected to the same power system as the air conditioner 11 are subjected to power factor improvement (compensation) only in accordance with their reactive currents, and are not subjected to active current compensation. That is, since the active filter device 4 does not compensate the active current of the other load device 20, it is not necessary to secure the capacity of the active filter device 4 corresponding to the other load device 20. Therefore, when another load device 20 is connected to the power system together with the air conditioner 11, the power factor can be improved without increasing the capacity of the active filter device 4 by applying the present embodiment. The present embodiment is useful for improving the power factor of a whole building or the like by utilizing the remaining power of the active filter device 4 incorporated in the air conditioner 11.
(modification of the fifth embodiment)
Fig. 8 is a block diagram showing an air conditioning system 100 according to a modification of the fifth embodiment. As shown in fig. 8, an air conditioning system 100 according to the present modification is an air conditioning system in which a low-pass filter 5138 is added to the active filter device 4 according to the fifth embodiment. In the present modification, an inductive motor 525 having a current without a harmonic component is connected to another load device 20 different from the air conditioner 11. In this case, the phase of the system current Is also changed to the lagging phase if nothing Is done.
In the present modification, as shown in fig. 8, the q-axis component of the dq converter 5128 is output as a q-axis component iq2 by passing through the low-pass filter 5138. Therefore, in the present modification, only the fundamental component of the reactive current of the load device 20 is compensated. That is, the present modification has a configuration useful in the case where the reactive current of another load device 20 does not include a harmonic component.
(sixth embodiment of the invention)
Fig. 9 is a block diagram showing an air conditioning system 100 according to a sixth embodiment of the present invention. The air conditioning system 100 is an example of an active filter device-equipped device, and incorporates an air conditioning device 11 and an active filter device 4. The air conditioning system 100 is provided in a building, a factory, an apartment, or the like. Power is supplied to a building or the like from a power system including an ac power supply 3. In this example, the ac power supply 3 is a three-phase ac power supply (commercial power supply). In addition, an impedance exists in the power grid of the power system (in fig. 9, a symbol indicating a coil is added between the ac power supply 3 and a distribution board 60 (described later) to indicate the impedance). Due to the phase modulation device 200, the phase of the current tends to be advanced in the process of supplying power from the ac power supply 3 to the distribution board 60. Due to the impedance, the power receiving voltage of the distribution board 60 becomes higher than that of the ac power supply.
A distribution board 60 is provided in the building or the like, and the distribution board 60 is connected to the ac power supply 3 and receives ac power from the ac power supply 3. The distribution board 60 includes a plurality of circuit breakers, and distributes the ac power from the ac power supply 3 to a plurality of devices via the respective circuit breakers. In this example, the air conditioning system 100 is connected to one of the circuit breakers described above. The air conditioning system 100 is operated by ac power supplied through the distribution board 60.
Specifically, the air conditioner 11 includes a refrigerant circuit (not shown) in which a refrigerant circulates to perform a refrigeration cycle operation, and cools or heats each room in a building or the like. The refrigerant circuit of the air conditioner 11 includes a compressor that compresses refrigerant. As shown in fig. 9, the air conditioner 11 includes a converter circuit 611, a reactor 612, a capacitor 613, an inverter circuit 614, and a motor 615.
The converter circuit 611 is a circuit that converts ac to dc. For example, the converter circuit 611 is constituted by a diode bridge circuit. The capacitor 613 is used to smooth the output of the inverter circuit 611. The inverter circuit 614 converts the dc smoothed by the capacitor 613 into an ac having a predetermined frequency and a predetermined voltage. Specifically, the inverter circuit 614 includes a plurality of (six in this case) switching elements connected in a bridge manner, and converts a direct current into an alternating current by turning on and off the input direct current.
The motor 615 of the air conditioner 11 is a so-called IPM motor. The motor 15 drives the compressor. Here, if the motor 615 Is operated without any processing, a harmonic current Is added to a current of the power system (hereinafter, referred to as a system current Is). That is, the air conditioner 11 is an example of a harmonic generation device. In the building and the like, power is supplied to load equipment (for example, an elevator and the like) other than the air conditioner 11 through the switchboard 60, and illustration thereof is omitted.
A phase modulation apparatus 200 is also provided in a building or the like. Fig. 10 schematically shows the structure of a phase modulation apparatus 200. As shown in fig. 10, phase modulation apparatus 200 includes three sets (corresponding to three phases) of series units constituted by phase-advance capacitors 201 and reactors 202 connected in series. As shown in fig. 10, each series unit is provided on the input side of the switchboard 60. Specifically, one end side of each series unit is connected to a predetermined one of the ac power supplies 3, and the other end sides of the series units are connected to each other. Note that, the current flowing in phase modulation apparatus 200 is hereinafter referred to as a phase advance capacitor current Isc.
< Structure of active Filter device >
As shown in fig. 9, the active filter device 4 includes a current source 6110, a power factor controller 6120, and a PWM controller 6140. In this example, the active filter device 4 is incorporated in the air conditioning system 100 together with the air conditioning device 11. The active filter device 4 allows a compensation current Ic, which will be described later, to flow through the power supply system, thereby improving the power factor and suppressing harmonics of the air conditioner 11. Here, as an example of the compensation current Ic, a direction from the active filter device 4 to the ac power supply 3 is set to be positive. Further, the sum of the system current Is and the compensation current Ic Is equal to the sum of the current (load current I1) flowing from the power supply system (ac power supply 3) to the air-conditioning apparatus 11 and the phase-advance capacitor current Isc flowing in the phase modulating apparatus 200.
-current source 6110-
The current source 6110 includes an inverter circuit 6111 and a capacitor 6113. The capacitor 6113 is formed of, for example, an electrolytic capacitor. The inverter circuit 6111 charges and discharges the capacitor 6113 by inputting and outputting the compensation current Ic. In this example, the inverter circuit 6111 is connected to the ac power supply 3 via a three-phase reactor 6160.
In the inverter circuit 6111 of the present embodiment, six switching elements 6112 are connected in a bridge manner, and illustration thereof is omitted. The inverter circuit 6111 changes the on/off state (on/off state) of the plurality of switching elements 6112 in synchronization with a carrier signal having a predetermined frequency, and inputs and outputs the compensation current Ic. On-off control of the switching element 6112 is performed by the PWM controller 6140. In this example, the low-pass filter 6150 is provided between the reactor 6160 and the connection point between the circuit breaker and the air conditioner 11 for the purpose of removing the ripple of the compensation current Ic. The low-pass filter 6150 is a so-called LC filter.
Power factor controller 6120
The power factor controller 6120 includes a power source phase detector 6121, a phase calculator 6122, three current sensors 6123, 6124, 6125, three dq converters 6126, 6127, 6128, a high-pass filter 6129, an adder 6132, three subtractors 6131, 6133, 6135, a voltage controller 6134, and two current controllers 6136, 6137. Specifically, the main portion of the power factor controller 6120 may be configured by a microcomputer, a memory in which software for operating the microcomputer is stored, or the like.
The power supply phase detector 6121 is connected to predetermined lines (any two of r-phase, s-phase, and t-phase) of the ac power supply 3, detects the phase of the line voltage, and outputs the detected phase to the phase calculation unit 6122. The phase calculation unit 6122 obtains the phase ω t between lines connected to the power supply phase detector 6121 using a signal (referred to as a zero-crossing signal S1) output from the power supply phase detector 6121. Phase calculation unit 6122 outputs the obtained phase ω t to dq converters 6126, 6127, and 6128.
The current sensor 6123 is provided outside the air conditioning system 100, and detects the load current I1. The load current I1 is a three-phase current, but the current sensor 6123 detects load currents ir1, it1 of two phases of the three phases. The current sensor 6124 detects the compensation current Ic. The compensation current Ic is also a three-phase current, but the current sensor 6124 detects load currents of two phases of the three phases.
The current sensor 6125 Is an example of a load information detection unit, and detects the system current Is. Here, the system current Is a current in the entire building or the like including the phase modulation apparatus 200. In this example, the current sensor 6125 is provided in the distribution board 60. That is, the current sensor 6125 is disposed outside the air conditioning system 100. The current sensor 6125 detects a current value (system current Is) at a position closer to the ac power supply 3 than the phase modulation apparatus 200 on the input side of the distribution board 60. The system current Is also a three-phase current, but the current sensor 6125 detects the system currents ir2, it2 of two of the three phases. The detected value (system current Is) of the current sensor 6125 Is wirelessly transmitted to the dq converter 6128. Of course, the detection value of current sensor 6125 may be transmitted to dq converter 6128 by a wired method.
It should be noted that, if the load current I1, the system current Is, and the compensation current Ic detect the current values of two phases of the three phases, the current value of the remaining one phase can be easily calculated, and therefore, each of the current sensors 6123, 6124, and 6125 may have a structure capable of detecting the currents of two phases. Further, the current sensors 6123, 6124, and 6125 may have various configurations. As an example of the current sensors 6123, 6124, and 6125, a current transformer can be given.
dq converter 6126 performs three-phase/two-phase conversion (dq-axis conversion) on load current I1 (three phase) obtained from the detection value of current sensor 6123. Here, the d-axis and the q-axis are axes in a rotation coordinate system that rotates in synchronization with the phase ω t obtained by the phase calculation unit 6122. The d-axis component obtained as a result of the conversion is an active current in the air conditioner 11. The dq converter 6126 outputs the d-axis component to the high-pass filter 6129. The q-axis component obtained as a result of conversion by the dq converter 6126 is a reactive current in the air conditioner 11. However, in the present embodiment, this q-axis component is not used for control.
The dq converter 6127 performs three-phase/two-phase conversion on the compensation current Ic obtained from the detection value of the current sensor 6124, and obtains a d-axis component (hereinafter referred to as d-axis current id) which is an active current and a q-axis component which is a reactive current. The d-axis current id is output to the subtractor 6135. In the present embodiment, the q-axis current obtained by dq converter 6127 is not used for control.
Further, dq converter 6128 performs three-phase/two-phase conversion on system current Is (three phases) obtained from the detection value of current sensor 6125, and obtains a q-axis component (hereinafter referred to as q-axis current iq). The q-axis current iq is a reactive current in the received current. In other words, it can be considered as a total value of reactive currents in a building or the like in which the active filter device 4 is installed. That is, the q-axis current iq is considered to be a q-axis component of a current to be caused to flow as the compensation current Ic. The q-axis current iq obtained by the dq converter 6128 is output to the subtractor 6131. In the present embodiment, the d-axis current obtained by dq converter 6128 is not used for control.
The high-pass filter 6129 removes a dc component from the d-axis component of the load current I1 output from the dq converter 6126, and outputs the d-axis component to the adder 6132. If there is no higher harmonic component in the load current I1, the output of the dq converter 6126 becomes dc. This is because a component synchronized with the phase of the alternating-current power supply 3 appears as direct current in the load current I1. That is, the high-pass filter 6129 outputs only the harmonic component included in the d-axis component of the load current I1 to the adder 6132.
If the compensation current Ic is made to flow so that the d-axis component and the q-axis component in the compensation current Ic match the harmonic component of the load current I1, the harmonic component of the load current I1 can be cancelled (hereinafter, the case where a current is made to flow so as to ensure cancellation of a predetermined component as described above is referred to as compensation). That is, the output of the high-pass filter 6129 can be used to generate a command value (d-axis current command value id ×) of the d-axis component (d-axis current id) of the compensation current Ic.
In this example, the output of the high-pass filter 6129 is corrected so that the output of the high-pass filter 6129 corresponds to a change in the voltage between the terminals of the capacitor 6113 (hereinafter, referred to as a dc voltage Vdc), instead of directly using the output of the high-pass filter 6129 as the d-axis current command value id. Specifically, in the power factor controller 6120, a subtractor 6133 first determines a deviation between the dc voltage Vdc of the capacitor 6113 and the command value Vdc thereof. The voltage controller 6134 performs proportional-integral control based on the deviation obtained by the subtractor 6133 to obtain a correction value. The correction value is added to the output of the high-pass filter 6129 by an adder 6132, and the addition result is output as a d-axis current command value id. The influence of the variation of the dc voltage Vdc is reduced.
The subtractor 6135 obtains a deviation Δ id obtained by subtracting the d-axis current id from the d-axis current command value id, and outputs the deviation Δ id to the current controller 6136. A fixed value (specifically, zero) is input to the subtractor 6131 as the q-axis current command value iq ″. The subtractor 6131 outputs a value (hereinafter referred to as a deviation Δ iq) obtained by subtracting the q-axis current iq from the q-axis current command value iq. The deviation Δ id is input to the current controller 6137.
The current controller 6136 outputs a d-axis voltage command value Vid, which is one of the voltage command values of the two phases, by using an algorithm such as feedback control (for example, so-called PID control) based on the deviation Δ id; the current controller 6137 outputs a q-axis voltage command value Viq, which is one of the voltage command values of the two phases, by an algorithm such as feedback control (for example, PID control) based on the deviation Δ iq.
PWM controller 6140-
The PWM controller 6140 generates a switching command value (drive signal G) for driving the current source 6110 from the d-axis voltage command value Vid and the q-axis voltage command value Viq. Specifically, the PWM controller 6140 performs so-called Pulse Width Modulation (PWM) control, and causes the current source 6110 to input and output the compensation current Ic. The PWM controller 6140 may be configured by a microcomputer, a memory in which software for operating the microcomputer is stored, or the like.
< working conditions of active filtering device >
Since active filter device 4 is incorporated in air conditioning system 100, power is supplied to air conditioning system 100 to operate active filter device 4. Then, in the power factor controller 6120, the q-axis current iq of the system current Is obtained from the detection value of the current sensor 6125 by the dq converter 6128. Further, the q-axis current command value iq is subtracted from the q-axis current iq by a subtractor 6131 to calculate the deviation Δ iq. In the power factor controller 6120, the dq converter 6126 and the like operate to generate a d-axis current command value id. The d-axis current id obtained by the dq converter 6127 is subtracted from the d-axis current command value id by the subtractor 6135 to calculate the deviation Δ id.
As soon as the deviation Δ id is determined, a d-axis voltage command value Vid is output from the current controller 6136; as soon as the deviation Δ iq is determined, the q-axis voltage command value Viq is output from the current controller 6137. As a result, the PWM controller 6140 outputs the drive signal G corresponding to the d-axis voltage command value Vid and the q-axis voltage command value Viq to the inverter circuit 6111.
For example, if the active filter device 4 Is not provided, when the load of the air conditioner 11 Is small, the phase of the system current Is leads to the phase of the advanced capacitor current Isc. However, in the present embodiment, the q-axis voltage command value Viq Is generated such that the q-axis component (q-axis current iq) in the system current Is becomes zero (q-axis current command value iq). On the other hand, a compensation current Ic having a component corresponding to the q-axis current command value iq flows from the current source 6110. As a result, in the present embodiment, the advance capacitor current Isc that has reached the leading phase is compensated, and the fundamental power factor in the received power is improved.
Note that the d-axis component of the compensation current Ic is adjusted for the air conditioner 11 to compensate for the higher harmonic component of the load current I1. Therefore, the harmonic components of the active current of the air conditioner 11 are also compensated. That is, the active filter device 4 can also reduce the harmonic current of the air conditioner 11.
< Effect of the present embodiment >
As described above, in the present embodiment, the reactive current of the entire building including the phase modulation device 200 is grasped and compensated. Therefore, in the present embodiment, the power factor in a building or the like having a phase modulation device can be improved.
(seventh embodiment of the invention)
Fig. 11 is a block diagram showing the configuration of a power factor control system 7000 according to the seventh embodiment. Power factor control system 7000 includes phase modulation apparatus 200 and air conditioning system 100.
The air conditioning system 100 is installed in a building, a single-family house, or the like (hereinafter, referred to as a building or the like), and conditions (cools or heats) air in each room. Power is supplied to the building and the like from a power system including the ac power supply 3. In this example, the ac power supply 3 is a three-phase ac power supply (e.g., a three-phase commercial power supply) and supplies power to the air conditioning system 100, which is a harmonic generation load. The air conditioning system 100 operates using ac power supplied from the ac power supply 3.
The phase modulation apparatus 200 is installed in a building or the like in order to improve the power factor of the whole building or the like.
< Structure of air conditioning system >
The air conditioning system 100 includes an air conditioning device 11 and an active filter device 4. The air conditioner 11 includes a refrigerant circuit (not shown) having a compressor and the power conversion device 1.
The refrigerant circuit of the air conditioner 11 is configured by connecting a compressor, an outdoor heat exchanger, an expansion mechanism, and an indoor heat exchanger to each other through refrigerant pipes. The refrigerant circuit is filled with a refrigerant, and the refrigerant circulates through the refrigerant circuit, whereby the interior of the room is cooled or warmed.
The power conversion apparatus 1 is connected to an ac power supply 3 via a phase modulation device 200, and has a converter circuit and an inverter circuit. When ac power is supplied from the ac power supply 3 to the power conversion device 1, the power conversion device 1 converts the ac power into ac power having a desired frequency and a desired voltage and supplies it to the compressor (more specifically, a motor included in the compressor). Thus, the compressor operates, and the refrigerant circuit functions. As a result, the indoor air is conditioned.
When the power conversion device 1 or the motor of the compressor operates, harmonic current may be generated in the air conditioner 11. The harmonic current may flow out to the ac power supply 3 through a current path for supplying power to the power converter 1. In general, the amount of harmonic current flowing out to the ac power supply 3 side is limited.
Therefore, the active filter device 4 is incorporated in the air conditioning system 100. The harmonic current generated in the power conversion device 1 is reduced by the active filter device 4.
From the viewpoint of equipment capacity and energy saving, etc., it is necessary to improve the fundamental wave power factor at the distribution side and the power reception side. In this case, the active filter device 4 also has a function of improving the fundamental power factor. The power factor of the power supply can be improved by improving the fundamental wave power factor in the active filter device 4.
The structure of the active filter device 4 will be explained below.
< Structure of active Filter device >
The active filter device 4 is connected in parallel to the ac power supply 3, and the power conversion device 1 that is a generation source of the harmonic current, and the active filter device 4 has a function of canceling the harmonic current that flows from the power conversion device 1 and appears in the power receiving path of the ac power supply 3. That is, the active filter device 4 causes the compensation current to flow so that the current waveform in the current path (hereinafter also referred to as the power receiving path 12) of the ac power supply 3 approaches a sine wave. More specifically, the active filter device 4 generates a compensation current having a phase opposite to that of the higher harmonic current appearing in the power receiving path 12, and supplies it to the power receiving path 12.
The active filter device 4 also has a power factor improving function of improving the fundamental power factor by allowing the above-described compensation current to flow. In this example, the active filter device 4 is configured to flow a compensation current for compensating also the reactive component of the fundamental wave, thereby improving the fundamental wave power factor.
In order to realize the above functions, as shown in fig. 11, the active filter device 4 according to the present embodiment includes a current source 730, filter device side current detectors 745a and 745b, a filter device side voltage detector 746, and an active filter device controller 743.
It should be noted that: when the load of the air conditioner 11 is maximum (for example, when the cooling output is maximum), the harmonic current generated in the air conditioner 11 is maximum. Therefore, the capacity, which is the capacity (the magnitude of the current or power that can be generated) of the active filter device 4, is set in accordance with the harmonic current when the load of the air conditioner 11 is at its maximum. This capacity is referred to as the output maximum capacity. However, in general, the air conditioner 11 is often used in a state where the load is smaller than the maximum load (for example, a medium load) as compared with a case where the air conditioner 11 is used in a state where the load is maximum. Then, it is conceivable: the active filter means 4 thus set to output maximum capacity is over-capacity for most of the operating time.
-current source-
The current source 730 generates a compensation current for reducing the higher harmonic current and improving the fundamental power factor. The output terminal of the current source 730 is connected to the power conversion device 1, and the generated compensation current is output to the power receiving path 12.
The current source 730 of the present embodiment is configured by a so-called inverter circuit (active filter inverter), and is not shown. A switching command value G described later is input from the active filter controller 743 to the current source 730. The current source 730 generates a compensation current by being turned on and off according to the switching command value G.
Current detector on the side of the filter device
Filter-side current detectors 745a and 745b detect current values Ir2a and It2a inputted to current source 730 of active filter device 4.
In this example, two filter-side current detectors 745a, 745b are provided in one active filter device 4. Filter-side current detector 745a detects R-phase current value Ir2a input from ac power supply 3 to current source 730, and filter-side current detector 745b detects T-phase current value It2a input from ac power supply 3 to current source 730. The current values Ir2a and It2a detected by the filter-side current detectors 745a and 745b are sent to the active filter controller 743.
The configuration of filter-device-side current detectors 745a and 745b is not particularly limited, and it is conceivable to use, for example, a current transformer or the like.
The filter-side current detectors 745a and 745b may be configured to transmit the detection result to the active filter controller 743 in a wired manner, or may be configured to transmit the detection result to the active filter controller 743 in a wireless manner.
In the present embodiment, the case where the filter-side current detectors 745a and 745b detect the two-phase output current values Ir2a and It2a of the ac power supply 3 is described as an example, but the filter-side current detecting unit may be configured to detect the three-phase output current value of the ac power supply 3.
A filter device side voltage detector-
The filter-side voltage detector 746 is connected to the R phase and S phase of the ac power supply 3, and is not connected to T. The filter-side voltage detector 746 detects only the line-to-line voltage Vrs of the ac power supply 3, and inputs the detected voltage Vrs to the active filter controller 743.
In the present embodiment, the case where the filter-side voltage detector 746 is connected to the two-phase output terminals of the ac power supply 3 is described as an example, but the filter-side voltage detector 746 may be connected to the three-phase output terminals of the ac power supply 3.
Active filter device controller
The active filter device controller 743 is constituted by a microcomputer and a memory storing a program for causing the microcomputer to operate. As shown in fig. 11, active filter controller 743 is connected to current source 730, filter-side current detectors 745a, 745b, filter-side voltage detector 746, and phase modulation apparatus controller 233 in phase modulation apparatus 200 described later. The active filter device controller 743 controls the output current (i.e., the compensation current) of the current source 730 as the active filter inverter unit based on the detection results of the detectors 745a, 745b, 746 and the current values Irs, Its of the ac power supply 3 transmitted via the phase modulation device controller 233.
< Structure of phase modulation apparatus >
As shown in fig. 11, in the power receiving path 12, a phasing apparatus 200 is connected between the output of the ac power supply 3 and the respective inputs of the power conversion device 1 and the active filter device 4. Phase modulation device 200 has a power meter 236, a phase modulator 233, and two phase modulation device controllers 231, 232. The power meter 236 is an example of the load information detection unit.
-phase modulator-
The phase modulators 231 and 232 are connected to the ac power supply 3 in parallel with the power conversion apparatus 1 and the active filter apparatus 4. The phase modulators 231, 232 control reactive power in the electric power supplied to the power conversion apparatus 1. In this example, phase modulation device 231 is a device capable of absorbing 20kVar of reactive power, and phase modulator 232 is a device capable of absorbing 50kVar of reactive power.
The phase modulators 231 and 232 are each composed of three phase advancing capacitors Ca, Cb, and Cc, three phase advancing reactors La, Lb, and Lc, and two switches 2311 and 2321 (corresponding to switching units). The reason why the phase modulators 231 and 232 are configured to include not only the phase advance capacitors Ca, Cb, and Cc but also the phase advance reactors La, Lb, and Lc is that: in the event of a short-circuit fault, the magnitude of the current flowing through the phase modulators 231, 232 can be reduced by the phase reactors La, Lb, Lc.
Switches 2311 and 2321 perform input and release of phase modulators 231 and 232 according to the switching signal of phase modulation device controller 233. That is, each of the switches 2311, 2321 is used to switch the corresponding phase modulator 231, 232 and the alternating-current power supply 3 to a connected state or a non-connected state.
Power meter (load information detection unit), etc.)
In the power reception path 12, a power meter 236, which is a load information detection unit that detects load information of the ac power supply 3, is connected between the output of the ac power supply 3 and the inputs of the phase modulators 231 and 232. The power meter 236 has two power supply side current detectors 234a, 234b and one power supply side voltage detector 235.
The power source side current detectors 234a and 234b detect output currents of the ac power source 3 before the current on the power receiving path 12 is branched toward the respective phase modulators 231 and 232 and the air conditioning system 100. In this example, two power source side current detectors 234a and 234b are provided. Specifically, the power supply side current detector 234a detects the current value Irs of the R-phase of the ac power supply 3; the power supply side current detector 234b detects a current value Its of the T phase of the ac power supply 3.
The power supply side voltage detector 235 is connected to output terminals of each phase of the ac power supply 3, and detects line voltages Vrs, Vst, and Vtr of the ac power supply 3, which are output voltages of the ac power supply 3.
The power meter 236, which is a load information detecting unit that detects load information of the ac power supply 3, may be a power meter or a smart meter installed in a building such as a building. In this way, sensors and detection circuits for measuring current and voltage can be omitted except for the power meter and the smart meter.
The configuration of the power source side current detectors 234a and 234b is not particularly limited, and a current transformer may be used, for example.
The power supply side current detectors 234a and 234b may be configured to transmit the detection results to the phase modulation device controller 233 in a wired manner, or may be configured to transmit the detection results to the phase modulation device controller 233 in a wireless manner. Note that the ac power supply 3 and the active filter device 4 may be separated by 20 to 30 meters. Therefore, if the active filter device 4 is connected from the power supply side current detectors 234a, 234b with wiring, it is necessary to arrange long wiring. In addition, the connection work itself of the power source side current detectors 234a, 234b and the active filter device 4 takes considerable time and effort. In contrast, by configuring to wirelessly transmit the detection results of the power source side current detectors 234a and 234b, the wiring itself is not necessary, and the wiring work is not required. If the existing transmission device exists near the power source side current detector, the existing transmission device may be wirelessly connected to the nearest connection point or the like and may transmit the information via the existing transmission device in the middle.
The magnetic flux passing through the power supply side current detectors 234a and 234b changes with time due to the current flowing through the power supply side current detectors 234a and 234b, and this phenomenon is referred to as electromagnetic induction. The electromotive force generated by the electromagnetic induction, i.e., the induced electromotive force, may be used as a power source (e.g., a power source for communication) for operating the power source side current detectors 234a and 234 b. The power supply-side current detectors 234a and 234b can thereby be operated without power supply (i.e., the power supply-side current detectors 234a and 234b do not require external power supply), and there is no need to perform a connection operation for connecting the power supply-side current detectors 234a and 234b to an external power supply.
In the present embodiment, the power meter 236, which is a load information detecting unit that detects load information of the ac power supply 3, is provided inside the phase modulation apparatus 200, but the power meter 236, which is a load information detecting unit that detects load information of the ac power supply 3, may be provided outside the phase modulation apparatus 200. Note that, as in the present embodiment, when power meter 236 is provided inside phase modulation apparatus 200, power meter 236 is not exposed to the weather, and therefore, the reliability of power meter 236 can be improved and the service life of power meter 236 can be extended.
The power source side current detectors 234a and 234b are not limited to detecting two phases of the ac power source 3, and may be provided for each of three phases of the ac power source 3.
Controller for phase modulation equipment
The phase modulation device controller 233 is constituted by a microcomputer and a memory storing a program for causing the microcomputer to operate. As shown in fig. 11, phase modulation device controller 233 is connected to power meter 236, respective switches 2311, 2321 in phase modulators 231, 232, and active filter device controller 743 in active filter device 4. The phase modulation device controller 233 calculates the reactive power P β and the power supply power factor θ α β from a signal from the power meter 236, or calculates information for grasping the reactive power P β and the power supply power factor θ α β. The phase modulation device controller 233 controls switching of the switches 2311 and 2321, and outputs detection results of the power supply side current detectors 234a and 234b to the active filter controller 743.
< switching control work for each switch by phase modulation device controller >
As shown in fig. 12, phase modulation device controller 233 includes a power factor calculation unit 2331 and a switching control unit 2332.
Power factor calculation section
The line-to-line voltages Vrs, Vst, and Vtr detected by the power supply side voltage detector 235 of the power meter 236 and the detection results Irs and Its of the power supply side current detectors 234a and 234b are input to the power supply power factor calculation unit 2331. The power factor calculator 2331 substitutes the input signal into the following equations (1 of 5) and (2 of 5) to calculate voltages V α and V β and currents i α and i β for two axes of rotation (α β axis).
[ equation 1 ]
Figure DEST_PATH_IMAGE001
[ formula 2 ]
Figure 179739DEST_PATH_IMAGE002
Next, the power factor calculating unit 2331 substitutes the voltages V α and V β and the currents i α and i β of the two axes of rotation (α β axis) obtained by the above equation (1 of the above equation (5)) and the above equation (2 of the above equation (5)) into the following equation (3 of the above equation (5)) and the following equation (4 of the below equation (5)), and calculates the active power P α and the reactive power P β.
[ formula 3 ]
Figure DEST_PATH_IMAGE003
[ formula 4 ]
Figure 181193DEST_PATH_IMAGE004
The active power pa and the reactive power P β are respectively substituted into the following expression (5 of 5), whereby the power factor θ α β of the ac power supply 3 can be obtained.
[ formula 5 ]
Figure DEST_PATH_IMAGE005
The above formula (5: 5) represents: the greater the reactive power P β, the lower the power factor θ α β of the power supply. Conversely, the smaller the reactive power P β, the higher the power supply power factor θ α β, and the higher (improved) the power factor. In the present embodiment, the reactive power P β is used to generate the switching signals of the phase modulators 231, 232, but the power supply power factor θ α β may be further calculated, or the reactive power P β and the power supply power factor θ α β may be further calculated and used to generate the switching signals of the phase modulators 231, 232.
Switching control section
The reactive power P β calculated by the power factor calculation unit 2331 is input to the switching control unit 2332. The switching control unit 2332 controls switching of the switches 2311, 2321 in the respective phase modulators 231, 232 in accordance with the reactive power P β to change a combination of connection states of the ac power supply 3 and the respective phase modulators 231, 232. Specifically, switching control unit 2332 substitutes reactive power P β into switching combination table 2332a of each of phase modulators 231, 232 of fig. 13, and performs logical decision to input each of phase modulators 231, 232 and to release each of phase modulators 231, 232. The switching control unit 2332 outputs a switching signal corresponding to the logical judgment to the switches 2311 and 2321 of the respective phase modulators 231 and 232.
Here, the switching combination table 2332a of fig. 13 is used as a reference for logical judgment, and four modes of 0kVar, 20kVar, 50kVar, and 70kVar can be put into combination with the phase modulator 232 of 20kVar and the phase modulation device 231 of 50 kVar.
In fig. 13, the range of the load (reactive power load range) represented by the reactive power P β is defined as four modes, for example, "0 kVar to 3 kVar", "3 kVar to 20 kVar", "20 kVar to 50 kVar", and "50 kVar to 70 kVar", and the connection state between each phase modulator 231, 232 and the power reception path 12 is represented for each mode. Such fig. 13 is predetermined before the power factor control system 7000 is built in the field or the like. In fig. 13, the case where the phase modulators 231 and 232 are connected to the power reception path 12 is referred to as "input", and the case where the phase modulators 231 and 232 are not connected to the power reception path 12 is referred to as "release". That is, the switches 2311, 2321 corresponding to the phase modulators 231, 232 labeled "release" leave the phase modulators 231, 232 and the power receiving path 12 in the non-connected state, and the switches 2311, 2321 corresponding to the phase modulators 231, 232 labeled "throw" leave the phase modulators 231, 232 and the power receiving path 12 in the connected state.
For example, in fig. 11 and 13, when the reactive power P β is gradually increased from 0kVar to 70kVar, the switches 2311 and 2321 perform switching operations in the following order (1) to (4).
(1) Either phase modulator 231, 232 is released from the power receiving path 12.
(2) While the phase modulator 231 of 50kVar is released from the power receiving path 12, the phase modulator 232 of 20kVar is put into the power receiving path 12.
(3) A20 kVar phase modulator 232 is released from the power receiving path 12, and a 50kVar phase modulator 231 is put into the power receiving path 12.
(4) While the 50kVar phase modulator 231 is put in the power receiving path 12, the 20kVar phase modulator 232 is put in the power receiving path 12 again (70 kVar in total).
Switching controller 2332 reduces the amount of input of phase adjusters 231 and 232 (specifically, phase advance capacitors Ca, Cb, and Cc) when reactive power P β is located in the leading direction (i.e., in a state where the compensation of phase advance capacitors Ca, Cb, and Cc for reactive power P β is excessive) with respect to a preset cutoff point (a threshold value defining the reactive power load range of fig. 13). In this case, the switching control unit 2332 also performs control such that: a combination of phase modulators 231 and 232 necessary and sufficient for compensating the reactive power P beta to be a load is selected, the selected phase modulators 231 and 232 are put in, and the other phase modulators 231 and 232 are released.
When the reactive power P β is controlled by only the phase modulation device controller 233, as shown by a thin solid line in fig. 14, the following state repeatedly occurs every time the phase modulators 231 and 232 are switched in a range of the reactive power P β of 0kVar to 70 kVar: at the switching timing of the connection state of each phase modulator 231, 232, the power supply power factor θ α β of the alternating-current power supply 3 temporarily becomes a leading phase more advanced than the target power, and then gradually approaches the target power.
Power factor improvement control by an active filter controller
In contrast, the active filter controller 743 controls the generation operation of the compensation current by the current source 730 of the active filter 4 so as to improve the leading power factor caused by the control of the reactive power P β by the phase modulation device controller 233 in accordance with the reactive power P β of the ac power supply 3. That is, by controlling the generation operation of the compensation current by the current source 730, the power supply power factor θ α β of the ac power supply 3 is further improved, and the power supply power factor θ α β is instantaneously converged to the target power factor.
As shown in fig. 15, the active filter device controller 743 includes a phase detector 7436, a first current calculator 7435, a second current calculator 7434, a load current calculator 7433, a current command calculator 7432, and a gate pulse generator 7431.
The line voltage Vrs of the ac power supply 3 detected by the filter-side voltage detector 746 is input to the phase detection unit 7436. The phase detector 7436 detects the phase of the power supply voltage in the power reception path 12 using the input line-to-line voltage Vrs, and outputs the detected phase to the first current calculator 7435 and the second current calculator 7434.
The phase of the power supply voltage detected by the phase detector 7436 and the current values Irs, Its of the ac power supply 3 detected by the power supply side current detectors 234a, 234b are input to the first current calculator 7435. The first current calculation unit 7435 obtains a current value (hereinafter referred to as a first current value i 1) necessary for performing both compensation of the harmonic current in the power reception path 12 (reduction of the harmonic current) and compensation of the reactive component of the fundamental wave (improvement of the fundamental wave power factor) from the input signal. First current calculator 7435 outputs the obtained first current value i1 to load current calculator 7433.
The phase of the power supply voltage detected by the phase detector 7436 and the current values Ir2a, It2a input to the current source 730 detected by the filter-side current detectors 745a, 745b are input to the second current calculation unit 7434. The second current calculator 7434 obtains a current value (hereinafter referred to as a second current value i 2) flowing through the active filter device 4 from the input signal. The active filter device 4 performs both the compensation of the harmonic current (reduction of the harmonic current) and the compensation of the reactive component of the fundamental wave (improvement of the fundamental wave power factor). The second current calculator 7434 outputs the obtained second current value i2 to the load current calculator 7433.
By subtracting the current values Ir2a, It2a input to the current source 730 of the active filter device 4 from the current values Irs, Its of the ac power supply 3, the total value of the currents flowing through the respective phase modulators 231, 232 of the power conversion device 1 and the phase modulation device 200, which are the sources of generation of harmonics, can be obtained. In the present embodiment, this is utilized to improve the fundamental wave power factor of the power conversion device 1 and the leading power factor of the phasing device 200, thereby improving the fundamental wave power factor of the power distribution terminal and the power reception terminal near the ac power supply 3 and reducing the harmonic current. That is, the active filter device 4 according to the present embodiment functions as a load for correcting the leading power factor of the phase modulation system 200.
Specifically, the load current calculation unit 7433 subtracts the second current value i2 of the second current calculation unit 7434 from the first current value i1 of the first current calculation unit 7435 to obtain the total value of the currents flowing through the respective phase modulators 231 and 232 of the power conversion device 1 and the phase modulation device 200, and outputs the obtained calculation result to the current command calculation unit 7432.
The current command calculation unit 7432 calculates the inverted current value of the calculation result of the load current calculation unit 7433, and outputs the value to the gate pulse generator 7431 as a current command value Iref.
The gate pulse generator 7431 generates a switching command value G that instructs the inverter circuit (active filter inverter) constituting the current source 730 to turn on or off. Specifically, the gate pulse generator 7431 performs so-called feedback control in which the operation of generating the switching command value G based on the deviation between the current value output from the current source 730 and the current command value Iref is repeated. Thus, a current (compensation current) corresponding to the current command value Iref is supplied from the current source 730 to the power receiving path 12.
More specifically, the gate pulse generator 7431 generates a switching command value G for matching the second current value i2 obtained by the second current calculator 7434 with the current command value Iref, and outputs the switching command value G to the current source 730. Harmonic components contained in the current flowing through the power conversion device 1 are thereby cancelled by the current output from the active filter device 4, and the output currents Irs, Itr, and Its of the ac power supply 3 are sinusoidal waves from which the harmonic currents are removed, thereby improving the power factor.
In the present embodiment, as described above, not only the current values Ir2a, It2a of the input current source 730 but also the current values Irs, Its of the ac power supply 3 are input to the active filter controller 743. Therefore, the active filter controller 743 can calculate the total value of the current flowing through each phase modulator 231, 232 and the current flowing through the power conversion apparatus 1, and can adjust the compensation current of the current source 730 based on the calculation result. As a result, the active filter controller 743 performs the following control through a series of controls: the actual power factor θ α β, which is affected not only by the power conversion apparatus 1 but also by the phase modulators 231, 232, is made to coincide with the target power factor.
In particular, the current source 730 of the active filter device 4 has a property that the power supply power factor θ α β becomes a power factor lagging behind the target power factor by operating. The active filter device controller 743 performs control for operating the current source 730 of the active filter device 4 so that the leading power factor caused by the phase modulators 231, 232 is cancelled by the lagging power factor caused by the active filter device 4, thereby converging the power factor θ α β of the ac power supply 3 to the target power factor.
The thin solid lines in fig. 14 indicate: power supply power factor θ α β in the state where phase modulation apparatus 200 operates under the control of phase modulation apparatus controller 233 described above and active filter device 4 is not operating. The dashed lines in fig. 14 indicate: phase modulation apparatus 200 is operated under the control of phase modulation apparatus controller 233 described above and the target power factor in a state where active filter device 4 is not operated. Each time phase modulation device controller 233 switches the connection state of each phase modulator 231, 232, power supply power factor θ α β temporarily becomes a leading power factor with respect to a target power factor and then gradually approaches the target power factor. Therefore, in fig. 14, the region of the power supply power factor θ α β to be compensated by the active filter device 4 is the region surrounded by the thin solid line and the dashed line.
In fig. 14, further indicated by thick solid lines: the power supply power factor θ α β when the active filter device 4 is in the state of operating under the control of the above-described active filter device controller 743. The power supply power factor θ α β indicated by a thick solid line in fig. 14 is substantially cancelled by the lag power factor caused by the active filter device 4, except that the leading power factor caused by the phase modulation apparatus 200 becomes the leading power factor only momentarily with respect to the target power factor when the phase modulators 231, 232 are switched. Therefore, the power supply power factor θ α β instantaneously converges to the target power factor as compared with the thin solid line. That is, this indicates that: by means of the active filter means 4 operating under the control of said source filter means controller 743, the region of the power supply factor theta alpha beta that the active filter means 4 should compensate for is compensated.
Therefore, power supply power factor control system 7000 according to the present embodiment can improve the leading power factor caused by phase modulation apparatus 200 by operating active filter device 4.
In the present embodiment, a case where one air conditioning system 100 is connected to the power reception path 12 is exemplified. If another device installed in a building such as a building is connected to the power receiving path 12, the power factor control system 7000 can reduce the leading power factor caused by the phase modulation apparatus 200 and improve the fundamental power factor of the entire building.
< Effect >
In contrast to the phase modulators 231, 232, when the active filter device 4 operates, the actual power supply power factor θ α β becomes a lagging power factor lagging behind the target power factor. In this embodiment, the following is improved by controlling the operation of the active filter device 4: the actual power supply power factor θ α β becomes a leading power factor leading the target power factor due to the phase modulators 231, 232 controlling the reactive power P β. Thus, the phenomenon that the actual power supply power factor θ α β becomes a leading power factor due to the phase modulators 231, 232 is simply improved, and thus, the appropriate compensation of the actual power supply power factor θ α β and the improvement of the fundamental power factor can be realized. As a result, it is possible to suppress an increase in power consumption of the power system of the ac power supply 3 and reduce the possibility of occurrence of a problem such as an unnecessary increase in the system voltage.
More specifically, the active filter device 4 is controlled to operate such that the leading power factor caused by the phase shifters 231 and 232 is cancelled by the lagging power factor of the active filter device 4, thereby converging the power factor θ α β of the ac power supply 3 to the target power factor.
In the present embodiment, the actual value of the reactive power P β used when controlling the power supply power factor θ α β can be easily obtained by calculating the detection results of the power supply side current detectors 234a and 234b and the detection result of the power supply side voltage detector 235.
A power meter 236 that measures power from an actual current value and an actual voltage value is connected to a building such as a building or a factory. The power meter 236 is an example of a load information detection unit that detects load information of the ac power supply 3. In the present embodiment, since the power meter 236 having the power supply side current detectors 234a and 234b and the power supply side voltage detector 235 is used, it is not necessary to separately install a sensor and a detection circuit for detecting current and voltage. As a result, the work of separately mounting the sensor and the detection circuit is not required, and the cost for installing the sensor and the detection circuit can be reduced.
In the present embodiment, the switching of the switches 2311 and 2321 is controlled in accordance with the reactive power P β of the ac power supply 3, and the combination of the connection states of the ac power supply 3 and the phase modulators 231 and 232 is appropriately changed. For example, the smaller the number of phase modulators 231, 232 that control the reactive power P β of the ac power supply 3, the lower the degree of leading power factor caused by the control of the phase modulators 231, 232 is suppressed, and the smaller the compensation amount of the active filter device 4 accordingly, the smaller the capacity of the active filter device 4.
In the present embodiment, the air conditioning system 100 (specifically, the power conversion device 1 in the air conditioning system 100) is a harmonic generation device, and the active filter device 4 is incorporated in the air conditioning system.
(other embodiments)
The active filter device 4 does not necessarily have to have a function of improving the fundamental power factor. That is, the active filter device 4 may be configured to have only a function of reducing the harmonic current. Further, the active filter device 4 may be configured to have only a function of improving the fundamental power factor.
The following may be configured: one air conditioner 11 is provided with a plurality of active filter devices 4. In this case, it is preferable that each active filter device 4 shares the compensation current according to its own current capacity.
As the load information detecting unit that detects the load information of the ac power supply 3, a device having a function of measuring the load information may be used to calculate and transmit a fundamental component, a power factor, reactive power, and the like of the current instead of the first current detecting unit 5 and the current sensor 6125. As an example of such a device, a so-called smart meter which is installed in a building or the like and transmits information such as a power consumption amount to a power company or the like can be cited. As described above, when a smart meter or the like is used, it is preferable that the active filter device is operated based on load information transmitted at predetermined time intervals, instead of the instantaneous information such as the current detector.
In the above embodiment, the controller 43 is mounted on the active filter device 4, but the controller 43 may be mounted in any place within the active filter device. For example, the controller 43 may also serve as a controller for controlling the power converter 1, and may be incorporated in the power converter 1, and illustration thereof is omitted.
Industrial applicability-
The present invention is useful as an active filter device built-in apparatus.
-description of symbols-
1 Power conversion device (loader)
2 load device
3 AC power supply
4 active filter device
4a current detector
4b current detector
4c current detector
5 first Current detecting section (load information detecting section)
11 air conditioner
30 current source
60 switchboard
100 active filter device built-in equipment

Claims (25)

1. An active filter device built-in apparatus which has an active filter device (4) built therein and is connected to an alternating current power supply (3), the active filter device built-in apparatus characterized in that:
the active filter device (4) is configured to: the load information detection unit (5) operates by determining the magnitude of the current (Ic) output from the active filter device (4) based on the detection value of the load information detection unit (5), and detects the load information of the AC power supply (3) from the outside of the device in which the active filter device is incorporated,
the active filter device (4) is controlled to work by a controller (43) installed in the active filter device built-in equipment,
the controller (43) determines the magnitude of the current (Ic) output from the active filter device (4) from the current value (iq 2) corresponding to the reactive current of another load device (20) connected to the AC power supply (3) and the current values (ir1, it1) of the current flowing from the AC power supply (3) to the active filter device-equipped equipment.
2. The active filter device built-in apparatus according to claim 1, characterized in that:
the active filter device (4) outputs a current for performing at least one of reduction of a harmonic current in the AC power supply (3) and improvement of a fundamental power factor in the AC power supply (3) based on the detection value.
3. The active filter device built-in apparatus according to claim 1, characterized in that:
the active filter device (4) uses only a fundamental component of the reactive current as the current value (iq 2) corresponding to the reactive current.
4. The active filtering device built-in apparatus according to any one of claims 1 to 3, wherein:
the load information detection unit (5) is configured to detect current values (Irs, Its), and the transmission method of the detected current values (Irs, Its) is a wireless method.
5. The active filtering device built-in apparatus according to any one of claims 1 to 3, wherein:
the load information detection unit (5) operates without a power supply.
6. The active filter device built-in apparatus according to claim 4, characterized in that:
the load information detection unit (5) operates without a power supply.
7. The active filtering device built-in apparatus according to any one of claims 1 to 3 and 6, wherein:
current detectors (4a, 4b, 4c) for detecting current values (Irs, Iss, Its) are provided in the load information detection unit (5) in correspondence with the respective phases (R, S, T) of the AC power supply (3).
8. The active filter device built-in apparatus according to claim 4, characterized in that:
current detectors (4a, 4b, 4c) for detecting current values (Irs, Iss, Its) are provided in the load information detection unit (5) in correspondence with the respective phases (R, S, T) of the AC power supply (3).
9. The active filter device built-in apparatus according to claim 5, characterized in that:
current detectors (4a, 4b, 4c) for detecting current values (Irs, Iss, Its) are provided in the load information detection unit (5) in correspondence with the respective phases (R, S, T) of the AC power supply (3).
10. An active filter device built-in apparatus which has an active filter device (4) built therein and is connected to an alternating current power supply (3), the active filter device built-in apparatus characterized in that:
the active filter device (4) is configured to: the load information detection unit (5) operates by determining the magnitude of the current (Ic) output from the active filter device (4) based on the detection value of the load information detection unit (5), and detects the load information of the AC power supply (3) from the outside of the device in which the active filter device is incorporated,
the alternating current power supply (3) is connected with a phase modulation device (200), the phase modulation device (200) is connected with the active filter device built-in device in parallel and is used for controlling the reactive power of the alternating current power supply (3),
the active filtering means (4) operates as a function of at least one of the reactive power and the power factor of the alternating current source (3) in order to improve the leading power factor due to the phase modulation device (200) controlling the reactive power.
11. The active filter device built-in apparatus according to claim 10, characterized in that:
the active filter device (4) outputs a current for performing at least one of reduction of a harmonic current in the AC power supply (3) and improvement of a fundamental power factor in the AC power supply (3) based on the detection value.
12. The active filter device built-in apparatus according to claim 10 or 11, characterized in that:
the load information detection unit (5) is configured to detect current values (Irs, Its), and the transmission method of the detected current values (Irs, Its) is a wireless method.
13. The active filter device built-in apparatus according to claim 10 or 11, characterized in that:
the load information detection unit (5) operates without a power supply.
14. The active filter device built-in apparatus according to claim 12, characterized in that:
the load information detection unit (5) operates without a power supply.
15. The active filtering device built-in apparatus according to any one of claims 10, 11, and 14, wherein:
current detectors (4a, 4b, 4c) for detecting current values (Irs, Iss, Its) are provided in the load information detection unit (5) in correspondence with the respective phases (R, S, T) of the AC power supply (3).
16. The active filter device built-in apparatus according to claim 12, characterized in that:
current detectors (4a, 4b, 4c) for detecting current values (Irs, Iss, Its) are provided in the load information detection unit (5) in correspondence with the respective phases (R, S, T) of the AC power supply (3).
17. The active filter device built-in apparatus according to claim 13, characterized in that:
current detectors (4a, 4b, 4c) for detecting current values (Irs, Iss, Its) are provided in the load information detection unit (5) in correspondence with the respective phases (R, S, T) of the AC power supply (3).
18. An active filter device built-in apparatus which has an active filter device (4) built therein and is connected to an alternating current power supply (3), the active filter device built-in apparatus characterized in that:
the active filter device (4) is configured to: the load information detection unit (5) operates by determining the magnitude of the current (Ic) output from the active filter device (4) based on the detection value of the load information detection unit (5), and detects the load information of the AC power supply (3) from the outside of the device in which the active filter device is incorporated,
the magnitude of the current (Ic) output from the active filter device (4) is determined by using the current value (iq) corresponding to the reactive current of a load (10) and a phase modulation device (200) other than the active filter device built-in device, which are connected to the AC power supply (3), and the current values (ir1, it1) of the current flowing from the AC power supply (3) to the load (10).
19. The active filter device built-in apparatus according to claim 18, characterized in that:
the active filter device (4) outputs a current for performing at least one of reduction of a harmonic current in the AC power supply (3) and improvement of a fundamental power factor in the AC power supply (3) based on the detection value.
20. The active filter device built-in apparatus according to claim 18 or 19, characterized in that:
the load information detection unit (5) is configured to detect current values (Irs, Its), and the transmission method of the detected current values (Irs, Its) is a wireless method.
21. The active filter device built-in apparatus according to claim 18 or 19, characterized in that:
the load information detection unit (5) operates without a power supply.
22. The active filtering device built-in apparatus according to claim 20, wherein:
the load information detection unit (5) operates without a power supply.
23. The active filtering device built-in apparatus according to any one of claims 18, 19, and 22, wherein:
current detectors (4a, 4b, 4c) for detecting current values (Irs, Iss, Its) are provided in the load information detection unit (5) in correspondence with the respective phases (R, S, T) of the AC power supply (3).
24. The active filtering device built-in apparatus according to claim 20, wherein:
current detectors (4a, 4b, 4c) for detecting current values (Irs, Iss, Its) are provided in the load information detection unit (5) in correspondence with the respective phases (R, S, T) of the AC power supply (3).
25. The active filtering device built-in apparatus according to claim 21, wherein:
current detectors (4a, 4b, 4c) for detecting current values (Irs, Iss, Its) are provided in the load information detection unit (5) in correspondence with the respective phases (R, S, T) of the AC power supply (3).
CN201780069144.4A 2016-12-09 2017-12-08 Active filter device built-in equipment Active CN110062999B (en)

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